When many groups of people are making a piece of equipment, like our CubeSat, they have to come up with interfaces that specify how different pieces will fit together. Then you make the pieces according to these interfaces and, if everyone has done everything correctly, the pieces should fit.
When we got our first prototypes of the structure, which will carry the mechanical loads, and the on-board computer, which also contains most of our payload, we decided to see if we’ve done everything well and our interfaces were maintained. And everything fits beautifully!
Isn’t it nice when a plan comes together?